XXII 



AUTUMN IN THE WOODS 



Although several of the flowers mentioned in the last chapter 

 as blooming during the present season may be seen along the 

 borders of woods, yet within the wood itself we are struck by the 

 almost total absence of flowers. This loss, however, is compensated 

 for by the beautiful and varied tints assumed by the leaves of the 

 trees and shrubs. 



Important changes are now taking place in these perennial 

 members of the vegetable world in preparation for the coming 

 winter. The temperature of the soil is becoming considerably 

 reduced, and, as a result, the absorbing activity of the roots is 

 greatly decreased, while the winter is coming, when the temperature 

 wiU be so low at times that the circulation of the sap will practically 

 cease. If the leaves remained on the trees, they would give off 

 from their smiaces more \\'ater than the trees could obtain from the 

 soil through their inactive roots, thus endangering the Uves of the 

 trees. The leaves, therefore, must be shed. But these leaves 

 contain a considerable amount of nutritious material which they 

 themselves have built up, and which should not be lost. They 

 contain starch, albumen, and other compounds which would be 

 entirely lost to the trees if the leaves were shed in their present 

 condition, except that a small proportion, in the form of products 

 of decomposition, might be re-absorbed. 



This being the case, arrangements must be made, first, for the 

 passage of the nutritious material in the leaves to some other part 

 of the tree where it can be stored for the winter ; and, second, for 

 the removal of the leaves as the roots become less active. 



So, before the time of leaf-fall, the nutritious substances in the 

 leaves, including the chloropliyll to which the leaf owes its green 

 colour-, become changed, and pass back to the stems or the root. 



